United Airlines becomes third major carrier to disclose it's been affected by suspicious engine parts

• Airlines have been on the lookout for potentially dodgy spare parts.
• The supplier has been under investigation by regulators who say it used false documentation.

United Airlines has joined the ranks of air carriers affected by inauthentic engine parts from a supplier called AOG Technics, Bloomberg reported.

The European Union Aviation Safety Agency issued a notification about the London-based supplier last month, suspecting unapproved parts.

It said AOG Technics had used false documentation for engine parts of unknown origin.

Bloomberg previously reported the dubious parts were used for repairs of CFM56 engines, which power many Airbus A320 and Boeing 737 planes, leaving companies scouring their records for references to the supplier. The total number of suspect spare parts is still unknown.

Since then, three major airlines have discovered that the components had been used in some of their engines.

A spokesperson for United told Bloomberg on Monday that bogus components were discovered in a single engine on two aircraft, one of which was already undergoing routine maintenance.

They didn't disclose which type of aircraft were affected, but said the parts helped direct airflow inside the engine.

Also on Monday, Virgin Australia Airlines found a second suspected unapproved part from AOG Technics, Bloomberg reported. Flightradar24 data showed the Boeing 737 in question was diverted during a flight on Saturday.

Southwest Airlines was the first major carrier to disclose that it had identified components from AOG Technics. "We became aware of the issue in early August and took necessary steps to ensure we do not have any parts in our fleet from AOG," a spokesperson said in a statement shared with Insider.

"Our suppliers conducted a review of Southwest parts and identified one engine that contained two low-pressure turbine blades from this vendor. In an abundance of caution, we made an immediate decision to promptly replace those parts on that single engine."

United and Virgin Australia did not immediately respond to Insider's request for comment, sent outside US and Australian working hours.